1. Field of the Invention
This invention relates to a link structure for a chain. In one specific embodiment of the invention, two identical, hollow U-shaped members having first and second parallel legs connected by a curved portion constitute the links; the U-shaped members are connected together to form a chain link which can be generally an oval in plan view. The first parallel leg of each one of the U-shaped members has a free end with a wall defining an opening for receiving an end portion of a free end of the second leg of the U-shaped member, The free end portion of each of second legs has a region of reduced outside diameter. The end portions of the first legs and the ends portions of the second legs are sized so that the latter have a sliding fit inside the former. When the two are assembled, they are locked against relative sliding movement by a ring which is received in cooperating slots provided on the end portions of the U-shaped members. The outer surfaces of the U-shaped members, when they are connected, cooperate to present a smooth outer chain link surface.
In a second embodiment, the link structure is produced from a link blank having first and second free ends which extend towards each other. The first free end has a wall defining an opening for receiving an end portion of the second free end of the link blank. The free end portion of the second free end has a region of reduced outside diameter. The wall of the first free end and the end portion of the second free end are sized so that the latter has a sliding fit inside the former. The link is produced by positioning a locking ring in a circumferential groove provided on the inside of the wall of the first end or in a circumferential groove provided on the free end portion of the second free end. The link blank is then manipulated, if necessary, to axially align the free ends, and the free end portion of the second free end is pressed into the first free end until the ends are locked against relative sliding movement by the ring which is then received in the circumferential groove provided on the inside of the wall of the first end and the circumferential groove provided on the free end portion of the second free end.
2. Description of Related Art
Metal chains are usually produced from individual links which are not closed, but have a transverse break somewhere along their longitudinal length. Such a link can be formed so that it is, when formed, mated with a second link, and the break in the link can then be closed by welding, This production method is entirely satisfactory for the production of chains whose appearance is comparatively unimportant, but gives rise to problems when a decorative chain is desired, for example where the exposed surface is plated with silver, brass, cadmium or the like, or carries another decorative finish. If welding is carried out before the plating or other finish is applied, it is difficult to achieve a satisfactory and continuous finish to the individual links of the chain because of contact points between individual links. On the other hand, if the finish is applied to the individual links before they are assembled, the welding step defaces the finish.
In some applications, heavy looking, large links are desired in chain which is not required to have great strength. When made of links which are solid, such chain becomes unreasonably and unnecessarily heavy.
A preliminary patentability study revealed the following references: U.S. Pat. No. 2,906,507, 1959, "Hodson"; U.S. Pat. No. 3,153,898, 1964, "Gerhardt"; U.S. Pat. No. 3,662,539, 1972, "Florjancie"; and U.S. Pat. No. 4,787,601, 1988, "Rybak".
Hodson discloses a chain produced from a plurality of links, each of which has a single transverse break, and a fence construction which includes a chain produced from a plurality of the links. To produce the chain, several of the links are assembled, and a clip is keyed to the exterior of each link to lock the free ends thereof against relative movement.
Gerhardt discloses a chain produced from a plurality of hollow links, each of which has it transverse break, or is composed of two parts, one of which has two ends that are slidably received in cooperating ends of the other. In both cases, glass or other fibers are impregnated with what the reference calls a "binding agent" which can be hardened by polymerization, placed inside the hollow links, and heated to harden the binding agent,
Florjancie discloses a chain produced by injection molding a first link into a second link.
Rybak discloses a chain composed of a plurality of generally "S" shaped links wherein at least one of the terminal portions of each link is slipped into the terminal portion of an adjacent link. In one embodiment, each link has a locking member which blocks the movement of one of the links into and out of the terminal portion of an adjacent link; the locking member can be easily deformed to enable movement into the terminal portion, but resists deformation to enable movement out of the terminal portion.
The attention of the inventor has also been called to the following patents because they were cited against an application which was directed to a different invention: U.S. Pat. No. 765,873, 1905, "Goldman"; U.S. Pat. No. 1,047,568, 1912, "Riess; U.S. Pat. No. 1,233,538, 1917, "Alden"; U.S. Pat. No. 1,507,808, 1924, Benjamin; U.S. Pat. No. 1,550,683, 1925, "Erikson"; U.S. Pat. No. 1,860,186, 1,932, "Kestenman"; U.S. Pat. No. 3,453,823, 1969, "Mundt"; U.S. Pat. No. 3,733,811, 1973, "Florjancic"; and U.S. Pat. No. 4,267,421, 1981, "Heppe". Of the foregoing patents, Goldman discloses hollow chain links formed of two link halves where the parting line is either longitudinal or transverse of the link halves, and members inside the assembled links which frictionally engage the two halves, and hold them in assembled relationship; Alden discloses connecting two completed links of a chain with a binder link that is opened at one end "and made of annealed or non-resilient metal that permits . . . [it] to be closed together without springing open"; Erikson discloses a link for a chain which is composed of two half links with transversely extending ends and lugs and depressions through which screws connect the half links; Florjancic discloses the production of a seamless chain by molding a link from a reinforced polyester or the like molding composition around a previously formed link; and Heppe discloses apparatus for "the successive welding of C-shaped, prebent interlinked chain links forming a chain." The others of the cited references are deemed to be less relevant, but to relate to various chain structures. No art was found showing a chain link composed of two abutting link parts, one of which has an end which is slidably received within a correspondingly shaped end of the other link, and an interior ring locking the two link parts in their abutting positions.